Soft core thermodynamics from self-consistent hard core fluids

TL;DR

This paper extends the SCOZA liquid-state theory to soft-core systems by combining it with a perturbation approach, improving predictions for fluids like Lennard-Jones by comparing with simulations.

Contribution

It introduces a novel combination of SCOZA with a perturbation theory for soft-core fluids, enabling more accurate thermodynamic predictions.

Findings

Enhanced accuracy in Lennard-Jones fluid predictions

Dependence of thermodynamics on effective hard-core diameter

Good agreement with simulation data

Abstract

In an effort to generalize the self-consistent Ornstein-Zernike approximation (SCOZA) -- an accurate liquid-state theory that has been restricted so far to hard-core systems -- to arbitrary soft-core systems we study a combination of SCOZA with a recently developed perturbation theory. The latter was constructed by Ben-Amotz and Stell [J. Phys. Chem. B 108,6877-6882 (2004)] as a reformulation of the Week-Chandler-Andersen perturbation theory directly in terms of an arbitrary hard-sphere reference system. We investigate the accuracy of the combined approach for the Lennard-Jones fluid by comparison with simulation data and pure perturbation theory predictions and determine the dependence of the thermodynamic properties and the phase behavior on the choice of the effective hard-core diameter of the reference system.